The present invention relates to an improved microscope. Further, the present invention relates to a stereoscopic microscope for imaging an object that can be placed in an object plane of the stereoscopic microscope, wherein the stereoscopic microscope provides at least one pair of imaging beam paths. The stereoscopic microscope comprises an imaging system with several optical elements, wherein the several optical elements comprise a plurality of lenses and at least one deflecting element having a mirror surface for deflecting the at least one pair of imaging beam paths.
Such microscopes, and especially stereoscopic microscopes, are used as surgical microscopes in medical applications, for example. The basic structure of a stereoscopic microscope such as known from the German laid open print DE 19 718 102 A1 is schematically shown in FIG. 8A.
According to FIG. 8A a stereoscopic microscope for imaging an object that can be placed in an object plane 41 comprises an objective lens 44, an aperture 45 and a variable magnification system with an inversion system 51. Further, on an exit side of the magnification system with inversion system 51, left sided and right sided optical imaging systems are provided. One pair of imaging beam paths 42a and 42b are commonly guided in the objective lens 44 and in the magnification system with inversion system 51. The optical beam paths 42a and 42b are guided separately in lenses 56 and 57 and 56′ and 57′ respectively of the left sided and right sided imaging systems. For achieving a stereoscopic effect, the imaging beam paths include a stereoscopic angle .alpha. in the object plane 41, the angle usually being between 4° and 8°.
The aperture 45 is used for altering the sensitivity of the stereoscopic microscope. For this purpose, a pupil plane 4A of an entrance pupil of the imaging beam paths 42a and 42b must be located in the vicinity of the aperture 45 and thus in between the objective lens 44 and the variable magnification system with inversion system 51.
In this respect, a pupil plane is considered to be a curved or flat plane in which central or main beams of beam bundles guided in the imaging beam path 42a and 42b intersect one another, wherein the central or main beams are emitted from different object points in the object plane 41.
The imaging system of the stereoscopic microscope shown in FIG. 8A further causes imaging of an intermediate image 4P within the variable magnification system with inversion system 51. Due to the minimal diameter of the beam bundle guided by the imaging system in the intermediate image this facilitates a threading of the beam bundles through the variable magnification system with inversion system 51.
In this respect, an intermediate image is considered to be a plane that is optically conjugated to the object plane 41.
A perspective view of selected elements of a stereoscopic microscope known from the prior art according to DE 19 718 102 A1 having the principal structure known from FIG. 8A is schematically illustrated in FIG. 8B.
As is evident from FIG. 8B, the stereoscopic microscopes known from the prior art comprise a plurality of deflecting elements 43, 46, 47, 49, 51, 52, 53 and 54, each comprising at least one mirror surface, to fold an imaging beam path 42 formed by the pair of imaging beam paths. The reason for this folding is that a total length of the structure of the stereoscopic microscope is to be made smaller. Due to this folding it is further possible to integrate an illumination beam path of an illumination system (not shown) via a deflecting mirror 43 located before the objective lens 44 neighboring the object plane 41 into the imaging beam path 42. Thus a 0° illumination of an object that can be placed in the object plane 43 is possible. To achieve this the mirror 43 has a surface which is semi-transparent. Furthermore, the folding causes an exchange of the pupils and an image inversion and thus corrects an exchange of the pupils and image inversion caused by the lenses 44, 50, 55 and the magnification system 48 of the stereoscopic microscope.
The structure of a stereoscopic microscope of the prior art described above has the following disadvantages:
Integration of 0° illumination system by using a semi-transparent mirror 43 causes substantial losses in both the illumination beam path and the imaging beam path. The reason is that the semi-transparent mirror does not completely deflect the imaging beams, and does not completely let pass the illumination beams guided in the illumination beam path. Consequently, the intensity of the beams emitted by the illumination system must be increased, which may cause heat problems in a surgical field and thus increase stress to the patient.
Furthermore, with an integration of a 0° illumination by using a semi-transparent mirror, the occurrence of reflections during transition of the illumination beams through the semi-transparent mirror that can be recognized in the imaging beam guided by the imaging beam path can only be avoided with large effort. The reason is that the imaging beam paths and the illumination beam path inherently overlap in the system of the stereoscopic microscope known from the prior art.
It is a further disadvantage of the structure known from the prior art that the structure uses eight deflecting elements for folding the imaging beam path and thus has a structure with a high volume. This structure with the high volume results from the fact that the user requires a stereoscopic microscope having one or two tube optics with oculars that can be freely pivoted, wherein one pair of imaging beam paths is guided to each tube optics with oculars. The reason is that the pairs of optical beam paths must be completely folded by a respective deflecting element even after pivoting of the respective tube.
A microscope-endoscope-examination system for examination of an object is known from DE 10 2004 059 143, the contents of which is completely incorporated by reference. The known system comprises an endoscope optics having a main optics with an endoscope beam path and a stereoscopic microscope beam path. A first and second optical element of the main optics is arranged next to an object plane of the stereoscopic microscope beam path and traversed, respectively, by a left and a right beam path of the stereoscopic microscope beam path. Central beam path axes of central beams of the respective left and right beam paths are arranged essentially in one common plane in between the object plane and the first respective second optical element, wherein all optical elements of the endoscope optics are at least partially arranged in between the two central beam axes when viewed in a projection to the common plane. However, the mounting of the known system is very cumbersome.
Starting from the above prior art it is an object of the present invention to provide a stereoscopic microscope having an improved structure in comparison to the prior art.